Beetling mill with closed casing



July 14, 1931. E. KRAMER BEETLING MILL WITH CLOSED CASING Filed F eb. 14'. 1929 1 myzzz vron.

ATTORNEY:

' g UNITED STA Patented July 14, 1931 TES PATENT OFFICE ERWIN KRAMER, F BERLIN, GERMANY, ASSIGNORTO HARTSTOFF mALL AK'IIEN- GESELLSCHAFT, OF BERLINKOPENICK, GER1VLANY BEETLING MILL WITH CLOSED CASING Application filed February 14, 1929, Serial No.

My invention relates to a beetling mill having a closed casing from which the ground material is discharged by means of an air current produced outside of said casing. The characteristic feature of this improved mill consists, firstly, in the particular configuration of the casing, secondly, in the arrangement of the openings through which the air current enters into, and leaves, that casing, and by which the path of the air in the casing is influenced, and thirdly, in the manner of introducing the material to be ground into the mill.

, power is required the action of such current in beetling members.

The thus improved mill has the advantage of presenting a co-mparativel smooth path for the compressed air so that only little to produce the air current; besides, the mill is very energetic which is very useful just for beetling mills in order to materially increase their efiiciency. Also a possibility is afiorded to provide passages of large sectional area for the compressed air without impairing the closed character of the casing. The strong current of the compressed air serves not only to increase the economy of the mill, in that it quickly removes the sufiiciently disintegrated material, but improves also the beetling action and efiect in that it diminishes the formation of cushions and air-buffers at thebeetling members, and one succeeds also, in fact, in attaining an increased degree of fineness of the product. Furthermore, the mere introduct1on of the material t9 be ground into a mill designed according to this invention has a similar efiect in that the material reaches instantly the most active zone of the And finally, the otherwise perceived disagreeable phenomenon which consists in particles just being ground being seized by the beetling members but being further disintegrated only in a very slight degree hardly worth mentioning, and sliding along said members, uselessly consuming work and power, and increasing the cushioning action arising at the said memhers, is greatly reduced.

All these defects I obviate and turn into the reverse by introducing either the air,

339,935, and in Germany February 17, 1928.

by the charging opening or branch being disposed at the outer circumference of the casing. Preferably also the discharging opening or branch is thus disposed. The arrangement is in either case preferably such that said openings or branches are located in the upper part of the mill casing and are directed tangentially with respect to the circles described by the free ends of the beetling members.

The invention is illustrated diagrammatically and by way of example on the accompanying drawings on which Fig. 1 is a vertical transverse section through a beetling mill designed according to this invention, while Fig. 2 is a vertical longitudinal section therethrough.

1 and 2 denote two pairs of beetling members ailixed to the rapidly rotating shaft 3 which is supported in the mill casing as shown'in Fig. 2. This casing consists of a central part a: and two lateral parts 5 and 6, the latter supporting said sha'ft. In transverse section the central part 4 is in its lower half of about semicircular shape, as shown in Fig. 1, while the adjacent wall portions extend vertically upwards, the entire wall of the middle portion 4 resembling thus, a U. Said vertical wall portions support a cover 7 in which openin s or passages 8 and 9 are provided. Above these openings or passages are-branches 10 and 11, of which 10 serves for the introduction 90 of the material and the air, and is, there-. fore, the charging branch, whereas 11 is the discharging branch. The openings 8 and 9 are located quite near the vertical wall portions of the U-shaped middle part of the casing.

The air from any suitable source'of supply such as the conventionally illustrated blower A, enters the mill casing in the direction indicated by the arrow 12 and is indicated by the arrow 14, whereafter thetwo currents unite with one another and pass out through the opening 9 and the branch 11. Owing to the alr traversing these paths,-the operating range of the beetlingmembers is thoroughly scavenged and the particles of the disintegrated and ground material are carried'away instantly after they have been formed. he corners 15 and 16 formed by the upper portions of the vertical walls and the adjacent portions of the horizontal cover may be regarded as coves withrespect to the space in which the beetling members. rotate; said corners or coves facilitate the spreading of the air current in the casing below the inlet openin 8, as well as the contraction of the same be ow the outlet opening 9, the result being a uniform scavenging of the entire casing, including, thus, the parts 5 and 6.

The particles falling down in the direction of the arrow 12 are encountered by the end portions of the beetling members which are rotating in the direction indicated by the arrow 17. Said particles contact, thus,

immediately after they have entered into the casing with the quickest moving portions of the beetling members where the disintegrating action is --most energetic, and owing hereto many particles leave the mill instantly thereafter through the branch 11 without having dropped down upon the bottom of the casing. f

The phenomenon of the particles circulatmg rotating beetling members and of the air rotating or circulating with them, as is generally perceived in closed mill casings, is greatly diminished by the coves 15 and 16 in that the moved particles leave the path of the beetling members and a part of them drop to the bottom, whereas the other part is first thrown against the cover 7 where the .respective particles are further disintegrated; only then they also drop to the bottom but in doing so are again encountered by the beetling members and are again subjected to disintegration. But while dropping through the lower half of the casing, the

particles are again and again acted on by the rapidly rotating beetlin members as they rotate in the direction 0 the arrow 17 i. e. counter to the air current which flows in the direction of the arrows" 12 and 14, and which, as is understood, is sufiiciently strong to overcome any counter air current or ourrents produced by 2 during rotation of the latter. v

" v Inorder to efiectively inter ce t particles whi h might be flung through" the opening .to time. Also,-

stances havin in the casing under the action of the V the beetling members 1 able; on a substantially an intercepting piece 8 into the branch 10,

branch, as shown in as a U and closing thispart by the horizontal cover 7 renders'it possible to obtain in a simple manner the cove-forming corners 15 and 16, and, on the whole, the entire construction of the middle part of the mill is rendered simple and allows this part being very conveniently opened so as to afford access to the interior of the entire mill in a very convenient manner, in that only the cover 7 need be removed. This latter is subjected to a somewhat strong wear and tear and-must be replaced, therefore, from time this replacing operation can be efiected quickly and conveniently.

The mill can be used for the disintegration or grinding of various materials or substances, but is especially suited for suba high specific gravity, for instancemeta s. V

- I claim:

1. A beetling mill comprising a closed casing, beetling elements therein rotatable on a horizontal axis, thetop of said casing having a passage therein disposed for the introduction of material to be treated and a current of air therethrough into the casing tangential to the path of travel of said beetling elements and counter to their direction of rotation, and means for introducin through saidpassage-a current of air I ciently strong to overcome any counter air current produced by the beetling elements durin theirrotation.

2. beetling mill comprising a closed casin on a orizontal axis, means at one sideof a vertical plane including said axis for the introduction'of material to be treated and a current of air downwardly through the top of said casing tangential to the path of travel of said beetling elements and counter to their direction of rotation, means at the other side of said plane for the discharge of the material throughthe top of said casing, and means for ing with the material to be treated a current of air sufliciently strong to overcome an counter air current produced by thebeetling elements during their rotation.

3. A beetling mill com rising" a closed casing of substantially U-s ape inclusive of a substantially semi-circularly shaped botbeetling elements within said casingv rotathorizontal axis,

, beetling elements therein rotatable introducing into the cas;

means at one side of a vertical plane including said axis for the introduction of material to be treated and a current of air downwardly through the top of said casing tangential to the path of travel of said beetling elements and counter to their direction of rotation, means at the other side of said plane for the discharge of the material through the top of said casing, and means for introducing into the casing with the material to be treated a current of air sufficiently strong to overcome any counter air current produced by the beetling elements durin their rotation.

4. beetlin mill comprising a closed casing, rotatab e beetlin elements within said casing, means forte introduction of material to be treated and a current of air 7 into said casing tangential to the path of V travel of the outer end ortions of said beetling elements, means or the discharge of the material from the casing, and means i i for introducing into the casing with the material to be treated a current of air sufiicientg5 1y strong to overcome; any counter air current produced by the beetling elements durrotation thereof.

n testimony whereof I aflix my signature. 

